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-   -   Lost Traction while braking (http://www.wranglerforum.com/f282/lost-traction-while-braking-166487.html)

Soccerghst09 06-13-2012 03:41 AM

Lost Traction while braking
 
Hey, so yesterday on my way to my soccer game, i lost traction while breaking a couple times. It had been raining all day, nothing hard, but a nice steady rain. Both times I lost traction was braking at a light on a downhill, and another time when trying to pass around a car turning left who suddenly decided to turn (that was the scary situation) They weren't very steep stops, but i guess steep enough. I might have lost traction on a flat stop as well (can;t remember, just know i did on the downhills). I hadnt had any problems in the rain before. I had got my jeep about 3 weeks ago, and the tires have good tread (almost brand new). However, I have been needing to change out my brake pads. I was wondering if the lack of traction had to do with the pads, or just the conditions and that i just need to be more aware and keep even more distance. I just felt that i didnt necessarily brake hard or suddenly, and was caught off guard that i lost traction. Anyway, thanks for the replies, i guess i'm happy i was able to avoid any collisions, and make to my game (4 assists=good game)

cork1958 06-13-2012 05:41 AM

How are the rear breaks? Rain, especially at the start, can be just as slippery as snow, as it washes off all the loose oil and stuff on the road too.

How were you passing a car turning left, if you were both going the same direction, especially if only on a 2 lane road?

Atthehop 06-13-2012 05:50 AM

I assume you mean your brakes were locking up. Since rain causes tires commonly used by jeeps to lose traction your brakes will lock up easier than tires found on cars. Plus most TJ's do not have anti lock brakes so you need to brake like the anti locks work.

s3nt3nc3d 06-13-2012 05:51 AM

As mentioned above, has it rained recently? After a dry spell, rain will bring up all the oils on the road which will make it slick as sh!t...I had never experienced this myself until a year or so ago. I was driving through downtown of a city up north of me and when I went to stop at a stop light I nearly went through it sideways. When I went to take off...same deal...slid all over the place trying to get traction. I was in my boss' Jeep Liberty...even using 4wd was still pretty slick. It was comparable to driving on an untreated road after freezing rain.

Kilroy 06-13-2012 06:09 AM

When you are going down hill, the weight of the vehicle is reduced, while the mass remains the same. Reduced weight means less traction to is available to stop the vehicle. Plus all of the above!

techflork 06-13-2012 09:31 AM

Quote:

When you are going down hill, the weight of the vehicle is reduced, while the mass remains the same. Reduced weight means less traction to is available to stop the vehicle. Plus all of the above!
I'm calling BS on that...you may be right in terms of work done by the weight. I suppose that could effect the friction needed. screw it I'm on summer break, no engineering problems for the next 3 months lol

anywhoo, I've run into the same situation a few times. Usually at start up it slips a little but I just need to start slower lol. There was a street that had just been laid down and it was raining. I went to stop at the light (just turned red quickly) and I slid the whole way through the intersection. Well slid half way then just gunned it cause I realized stopping was pointless haha. Luckly it just turned red for me so no cars were moving.

jgorm 06-13-2012 09:39 AM

Quote:

Originally Posted by techflork (Post 2468013)
I'm calling BS on that

I'm with you on that. Weight = mass when you are on earth. The mass vector will decrease the tire traction when you are going downhill because it has a component in your direction of travel.

Kilroy 06-13-2012 09:47 AM

[QUOTE=techflork;2468013]I'm calling BS on that...you may be right in terms of work done by the weight. I suppose that could effect the friction needed. screw it I'm on summer break, no engineering problems for the next 3 months lol

It is just physics. Ignoring wind or other resistance, imagine your jeep free falling towards earth. It is weightless, just like in astronaut training. It still has mass, but no weight. Driving downhill is a like a slow fall. Your jeep is not weightless, but the weight is reduced. And that reduces the pressure holding your tires to the road. Going uphill is just the opposite!

Kilroy 06-13-2012 09:53 AM

Quote:

Originally Posted by jgorm (Post 2468049)
I'm with you on that. Weight = mass when you are on earth. The mass vector will decrease the tire traction when you are going downhill because it has a component in your direction of travel.

Not when falling!

Soccerghst09 06-13-2012 10:43 AM

The car was making a left into a sidestreet, They had signalled late, and braked late. However, like many do, when there is space to the right of the vehicle that is waiting to turn due to traffic, they pass to the right of the vehicle in order to get around and continue, rather than wait for the car turning left to turn.

InvertChaos 06-13-2012 10:46 AM

Quote:

Originally Posted by jgorm
I'm with you on that. Weight = mass when you are on earth. The mass vector will decrease the tire traction when you are going downhill because it has a component in your direction of travel.

Not when falling. Have you ever seen those "zero g" flights they'll take you on? You become weightless relative to the plane. Weight changes, mass does not.

lynn 06-13-2012 10:55 AM

What kind of tires?
Siping and rubber compound both strongly influence wet braking ability... in other words, given the same road conditions and braking force, some tires will skid before others.
As Atthehop mentioned above, tires we commonly run on Jeeps such as mud-terrain and some all-terrain will tend to skid more quickly than a quality street tire such as Michelin cross-terrains (the wet-braking and wet-acceleration grip I had with Michelin cross-terrains on a ZJ was simply amazing compared to my mud-terrains on the LJ!)

Shadowkraze 06-13-2012 10:56 AM

[QUOTE=Kilroy;2468072]
Quote:

Originally Posted by techflork (Post 2468013)
It is just physics. Ignoring wind or other resistance, imagine your jeep free falling towards earth. It is weightless, just like in astronaut training. It still has mass, but no weight. Driving downhill is a like a slow fall. Your jeep is not weightless, but the weight is reduced. And that reduces the pressure holding your tires to the road. Going uphill is just the opposite!


Right well we need to factor in velocity and slope also if we really want to get into this one.
However, you do get a shift in weight while braking (more on the slope) thanks to suspension. I will break traction on a slight slope when wet as opposed to flat ground because I've raised my center of gravity. Thus when I brake on the slope the transfer of weight shifts forward (on the vehicle) causing less friction on the back tires, my back tires lose traction during braking because of this factor and others.

Miguzi 06-13-2012 11:12 AM

Happened to me twice a few days ago... after it rained. Both times coming up to a red light and behind a car. Good thing I went into the curb both times though else I would have destroyed that corvette...

jgorm 06-13-2012 02:42 PM

Quote:

Originally Posted by InvertChaos (Post 2468262)
Not when falling. Have you ever seen those "zero g" flights they'll take you on? You become weightless relative to the plane. Weight changes, mass does not.

That's why I said "on earth". I should have also said that the weight can change based on the g forces encountered from relative movements.

Atthehop 06-13-2012 03:23 PM

Quote:

Originally Posted by Miguzi (Post 2468364)
Happened to me twice a few days ago... after it rained. Both times coming up to a red light and behind a car. Good thing I went into the curb both times though else I would have destroyed that corvette...

Driving too fast and following too close. I have learned to stop doing that, biggest offender for years, and learned to keep an eye out for the person behind me so if I feel they cannot stop I will take evasive action so the hit the person I front of me.

GoldenSahara00 06-13-2012 03:48 PM

Love the physics debates. Seeing as weight is force and force is mass times acceleration, then you are driving down a hill one component of that is downwards, decreasing the net accessions caused by earths gravity. Therefore reducing the weight. That's just laymens terms for anyone whose not science savvy.

Anyways. Drive slower break easier. Be more cautious. That's not unheard of in jeeps when stopping in rain.

Miguzi 06-13-2012 04:04 PM

Quote:

Originally Posted by Atthehop

Driving too fast and following too close.

Nah. I was extremely cautious that day. Few cars length away and braking far back. First time driving in Houston with that weather... But after I slid those two times... I started staying even further from other cars and creeping up to the light.

Soccerghst09 06-13-2012 06:51 PM

thanks for the replies...i'll try and get back to you about what tires i have...again, i just got it a few weeks ago so everything is stock, but the tires seemed to have been purchased recently, but arent off road tires. i certainly kept a further distance, and began breaking even further back. i'm not so worried about normal driving situations, but more so in evasive emergency situations where i need to slam on the brakes or avoid cars. again thanks for the replies, i'm gonna change my pads soon so hopefully that'll help as well, and when i can get better tires.

Kilroy 06-13-2012 07:05 PM

Check to see if your brakes are stock, or if a PO midified them. Unless you have a Rubicon, stock means disk in fornt and drum in rear. There should be a proportioning valve that properly apportions brake pressure to front and rear brakes.

lynn 06-14-2012 07:05 AM

Tire inflation is a factor too. What air pressure are you running?

Soccerghst09 06-15-2012 01:24 AM

so i checked, the tires are kelly safari trex...stock size on 15 rims. checked some reviews, and it seems mixed, one guy however did say they are horrible on wet,dry,sandy,etc pavement, so it might be that i need better tires. if you know anymore on the tires and have experience with them, and could offer your opinion, i'd appreciate it.

Atthehop 06-15-2012 05:50 AM

I have been running BFG AT's for over 12 years and they wear like iron and handle well on wet and snowy roads. I commuted 100 miles a day before getting laid off 3 months ago with these tires and had over 80k on my 30x9.5's before upgrading to 31x10.5's last fall.


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